Implants in dentistry have been used for a considerable time, and one of the first clinical examples of their use as an orthodontic anchor was presented by Creekmore1. Since that time, a number of investigators have presented modifications of the Creekmore implant including Kanomi in 19972, Melsen et al. in 19983, Mazzocchi and Bernini in 19984, Roberts et al. in 20005, Park et al. in 20016, Chung et al in 20027 and Maino et al in 20038. In all of these embodiments, single screw type implants are placed in buccal or labial positions which then can be used to apply a force to intrude, protract or retract one or more teeth within the same dental arch. This force is generated by attaching a spring or elastomeric material from the implant to the teeth to be moved. The resultant force vector will assure the movement of teeth along this vectorial line. However, should it not be desirable to move teeth in this direction, changes in this vector cannot be accomplished.
Heretofore, it has not been possible to apply a force at some distance from the emergence of the implant from the soft tissue. That is, the location where the anchor emerges from the bone or gingiva has always been used as the point of attachment or resistance of force from the anchor to some distant tooth or teeth.
To alter the direction of this force from the implant to a point distant therefrom has not been proposed nor is it possible to accomplish with a simple screw implant. This becomes readily apparent when one considers the great moments which would be generated if a lever arm extension projected from the screw implants. The screw would tend to rotate easily as the length of the arm increased thereby increasing the moment.
The onplant, first described by Block and Hoffman, can withstand torquing moments but it cannot be placed anywhere except in the palate. Its bulk and thickness require that it be covered by palatal mucosa, but the thin mucosa covering the buccal bone in the vestibules of both the maxillary and mandibular arches is not conducive to the placement of this type anchor.
Thus, mechanisms to intrude individual teeth or to move teeth anteriorly or posteriorly from the screw are available but there has been no ability to manipulate the direction of the force vector or to apply the force at some distance remote from the implant. Additionally it has not been possible with current implant technology to impact an entire dental arch with favorable and varying force vectors whose directions can be changed easily at the discretion of the clinician. Furthermore, it has not been possible, prior to this invention, to extrude individual or groups of teeth.
Implants that would permit force application to be some distance from the center of insertion of the implant could be skeletal implants as used in surgical procedures. The use of these skeletal implants for the movement of teeth was presented by Umerori et al. in 19989. With these skeletal implants, the posterior dentition was intruded but there was no mechanism by which the intrusion force could be delivered selectively to different parts of the dentition, i.e., there was no ability to deliver a pure intrusion force component to any part of the dentition without an accompanying and often undesirable horizontal component. The extrusion of teeth was not possible nor considered by the presentation of Umerori. Thus, at present, there is no mechanism by which the clinician can easily deter or manipulate the direction of force from an implant to one or more teeth.